Although Isaiah Berlin liked to say that he left philosophy for the history of ideas after the Second World War, there is a decided continuity between his more purely philosophical writings, most of which are collected in this volume, and the more historical work for which he is better known.

Included here are Berlin's early arguments against logical positivism and later essays which more evidently reflect his life-long interest in political theory, intellectual history and the philosophy of history.

In two related pieces he gives his view on the philosopher's task, to uncover the various models - the concepts and categories - that we bring to our experience, and that help to form it. In his own words 'The goal of philosophy is always the same, to assist men to understand themselves and thus operate in the open, and not wildly, in the dark.'

Isaiah Berlin was born in Riga, now capital of Latvia, in 1909. When he was six, his family moved to Russia, and in Petrograd in 1917 Berlin witnessed both Revolutions - Social Democratic and Bolshevik. In 1921 he and his parents emigrated to England, where he was educated at St Paul's School, London, and Corpus Christi College, Oxford. Apart from his war service in New York, Washington, Moscow and Leningrad, he remained at Oxford thereafter - as a Fellow of All Souls, then of New College, as Chichele Professor of Social and Political Theory, and as founding President of Wolfson College. He also held the Presidency of the British Academy.

His published work includesKarl Marx, Russian Thinkers, Concepts and Categories, Against the Current, Personal Impressions, The Sense of Reality, The Proper Study of Mankind, The Roots of Romanticism, The Power of Ideas, Three Critics of the Enlightenment, Freedom and Its Betrayal, Liberty, The Soviet MindandPolitical Ideas in the Romantic Age. As an exponent of the history of ideas he was awarded the Erasmus, Lippincott and Agnelli Prizes; he also received the Jerusalem Prize for his lifelong defence of civil liberties. He died in 1997.